PCVL-1147 support for coherent light inputs

[Aubaert]

No description provided.

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CoherentState.__ne__ currently recurses:

def __ne__(self, other: CoherentState) -> bool:
    return not self != other

So any != comparison raises RecursionError:

CoherentState([1]) != CoherentState([2])

Local check on this PR branch:

eq_same True
eq_diff False
ne_diff_error RecursionError maximum recursion depth exceeded
ne_same_error RecursionError maximum recursion depth exceeded

A direct fix is:

def __ne__(self, other: CoherentState) -> bool:
    return not self == other

A regression test can cover both equal and non-equal states:

assert not (CoherentState([1]) != CoherentState([1]))
assert CoherentState([1]) != CoherentState([2])